Abstract: Five sodium alginate and gelatin-based films incorporated with ellagic acid were prepared at different pH values by casting method. The properties and structure of the films were characterized by opacity, mass loss percentage, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, the diameter of inhibition zone of bacterial growth, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The results indicate that opacity, DPPH radical scavenging activity of the films was increased significantly by adding ellagic acid, and the film properties were also affected by changing pH. All the blended films exerted antibacterial activity against Escherichia coli, Salmonella and Staphyloccocus aureus especially against Gram-negative bacteria (E. coli and Salmonella). The film prepared at pH 9.0 had the best performance, with opacity of 15.54, water solubility of 0.38%, water vapor transmission coefficient of 0.74 × 10－10 g/(m·s·Pa), and DPPH radical scavenging rate of 57.42%. According to the FTIR spectra and SEM, all films had a complete morphology and structure, and were well cross-linked with good compatibility.

Key words: sodium alginate, gelatin, ellagic acid, blended films